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Enzymatic hydrolysis of the gelatinous layer in tension wood of Salix varieties as ameasure of accessible cellulose for biofuels

Gao, Jie and Jebrane, Mohamed and Terziev, Nasko and Daniel, Geoffrey (2021). Enzymatic hydrolysis of the gelatinous layer in tension wood of Salix varieties as ameasure of accessible cellulose for biofuels. Biotechnology for Biofuels. 14 , 141
[Research article]

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Abstract

Background Salix (willow) species represent an important source of bioenergy and offer great potential for producing biofuels. Salix spp. like many hardwoods, produce tension wood (TW) characterized by special fibres (G-fibres) that produce a cellulose-rich lignin-free gelatinous (G) layer on the inner fibre cell wall. Presence of increased amounts of TW and G-fibres represents an increased source of cellulose. In the present study, the presence of TW in whole stems of different Salix varieties was characterized (i.e., physical measurements, histochemistry, image analysis, and microscopy) as a possible marker for the availability of freely available cellulose and potential for releasing D-glucose. Stem cross sections from different Salix varieties (Tora, Björn) were characterized for TW, and subjected to cellulase hydrolysis with the free D-glucose produced determined using a glucose oxidase/peroxidase (GOPOD) assay. Effect of cellulase on the cross sections and progressive hydrolysis of the G-layer was followed using light microscopy after staining and scanning electron microscopy (SEM). Results Tension wood fibres with G-layers were developed multilaterally in all stems studied. Salix TW from varieties Tora and Björn showed fibre G-layers were non-lignified with variable thickness. Results showed: (i) Differences in total % TW at different stem heights; (ii) that using a 3-day incubation period at 50 °C, the G-layers could be hydrolyzed with no apparent ultrastructural effects on lignified secondary cell wall layers and middle lamellae of other cell elements; and (iii) that by correlating the amount of D-glucose produced from cross sections at different stem heights together with total % TW and density, an estimate of the total free D-glucose in stems can be derived and compared between varieties. These values were used together with a literature value (45%) for estimating the contribution played by G-layer cellulose to the total cellulose content. Conclusions The stem section-enzyme method developed provides a viable approach to compare different Salix varieties ability to produce TW and thus freely available D-glucose for fermentation and biofuel production. The use of Salix stem cross sections rather than comminuted biomass allows direct correlation between tissue- and cell types with D-glucose release. Results allowed correlation between % TW in cross sections and entire Salix stems with D-glucose production from digested G-layers. Results further emphasize the importance of TW and G-fibre cellulose as an important marker for enhanced D-glucose release in Salix varieties.

Authors/Creators:Gao, Jie and Jebrane, Mohamed and Terziev, Nasko and Daniel, Geoffrey
Title:Enzymatic hydrolysis of the gelatinous layer in tension wood of Salix varieties as ameasure of accessible cellulose for biofuels
Series Name/Journal:Biotechnology for Biofuels
Year of publishing :2021
Volume:14
Article number:141
Number of Pages:18
ISSN:1754-6834
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Wood Science
Keywords:Salix viminalis, Bioenergy crops, Enzymatic saccharification, Lignocellulose biofuels, Biomass recalcitrance
URN:NBN:urn:nbn:se:slu:epsilon-p-112507
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-112507
Additional ID:
Type of IDID
DOI10.1186/s13068-021-01983-1
ID Code:24672
Faculty:S - Faculty of Forest Sciences
Department:(S) > Department of Forest Biomaterials and Technology
Deposited By: SLUpub Connector
Deposited On:23 Jun 2021 11:23
Metadata Last Modified:23 Jun 2021 11:31

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